OC-UI阶段学习10-UIControl与子类：UISlider，UISegmentControl

一、UISlider

UISlider是iOS中的滑块控件

通常用于控制视频播放进度，控制音量

它继承于UIControl，滑块位于滑条不同位置时提供不同的Value值

    //滑竿初始化
    UISlider *mySlider = [[UISlider alloc]initWithFrame:CGRectMake(22, 22, 300, 50)];
    
    //设置滑竿值范围
    mySlider.minimumValue = 0.5;
    mySlider.maximumValue = 3;
    //设置起始值
    mySlider.value = 1;
    
    //设置滑过范围的颜色
    mySlider.minimumTrackTintColor = [UIColor grayColor];
    //未滑过的颜色
    mySlider.maximumTrackTintColor = [UIColor redColor];
    
    //指定左边和右边指示图 图像大小30X30
    mySlider.minimumValueImage = [UIImage imageNamed:@"bc.jpg"];
    mySlider.maximumValueImage = [UIImage imageNamed:@"bc.jpg"];
    //设置滑块的颜色
    mySlider.thumbTintColor = [UIColor greenColor];
    mySlider.tag = 1004;

    //设置滑块的图片
    [mySlider setThumbImage: [UIImage imageNamed:@"bc.jpg"]forState:UIControlStateNormal];
 
    //添加触发事件，滑动滑竿触发
    [mySlider addTarget:self action:@selector(changeTransform:) forControlEvents:UIControlEventValueChanged];

    //添加到父视图
    [self.view addSubview:mySlider];

可以练习创建三个UISlider，通过它们改变背景的RGB值，达到调节背景颜色的效果,没啥难度

二、UISegmentControl

UISegmentControl是iOS中常用的分段控件，它相当于集成了多个Button

可以使用分段控件切换不同的视图

//初始化，items 根据数组在的元素创建相应个数的按钮
    UISegmentedControl *segmentedControl = [[UISegmentedControl alloc]initWithItems:[NSArray arrayWithObjects:@"红",@"绿",@"蓝", nil]];
    
    //设置大小
    segmentedControl.frame = CGRectMake(100, 100, 200, 50);
    
    //指定被选中的分段
    segmentedControl.selectedSegmentIndex = 0;
    [segmentedControl setSelectedSegmentIndex:1];
    
    //更改分段控制器颜色
    [segmentedControl setTintColor:[UIColor grayColor]];
    
    //给每个分段设置图片
    //渲染模式imageWithRenderingMode 设置 为UIImageRenderingModeAlwaysOriginal
    //否则会根据当前的颜色对图片进行颜色渲染
    [segmentedControl setImage:[[UIImage imageNamed:@"bc.jpg"] imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal] forSegmentAtIndex:1];
    
    //添加点击事件
    [segmentedControl addTarget:self action:@selector(changeBgColor:) forControlEvents:UIControlEventValueChanged];
    
    //设置样式，已经废弃
   // segmentedControl.segmentedControlStyle
    
     [self.view addSubview:segmentedControl];

下面做一个小练习，通过UISegmentControl改变视图的颜色

#pragma mark  三个界面通过分段控制器切换
    
    //创建三个视图
    for (int i = 0; i < 3; i ++) {
        UIView *view = [[UIView alloc]initWithFrame:CGRectMake(0, 300, 375, 300)];
        view.tag = 1000+i;
        //设置背景色为随机
        view.backgroundColor = [UIColor colorWithRed:arc4random()%256/255.0 green:arc4random()%256/255.0 blue:arc4random()%256/255.0 alpha:1];
        [self.view addSubview:view];
//        if (i == 0) {
//            view.hidden = NO;
//        }
//        else
//            view.hidden = YES;
    }
    
    //创建分段控制器
    UISegmentedControl *changeViewSegment = [[UISegmentedControl alloc]initWithItems:[NSArray arrayWithObjects:@"1",@"2",@"3", nil]];
    changeViewSegment.frame = CGRectMake(80, 100, 200, 30);
    
    //默认选中第一个分段，设置tag值
    changeViewSegment.selectedSegmentIndex = 0;
    changeViewSegment.tag = 1003;
    
    //添加方法，点击分段切换颜色
    [changeViewSegment addTarget:self action:@selector(changeView:) forControlEvents:UIControlEventValueChanged];
    [self.view addSubview:changeViewSegment];

<pre name="code" class="objc">//segment切换视图方法

 -(void)changeView:(UISegmentedControl*)sender
{
    //根据Tag值得到三个视图
    UIView *firstView = [self.view viewWithTag:1000];
    UIView *secondView = [self.view viewWithTag:1001];
    UIView *thirdView = [self.view viewWithTag:1002];
    
    //通过修改三个视图的hidden属性实现切换
    switch (sender.selectedSegmentIndex) {
        case 0:
            firstView.hidden = NO;
            secondView.hidden = YES;
            thirdView.hidden = YES;
            break;
        case 1:
            firstView.hidden = YES;
            secondView.hidden = NO;
            thirdView.hidden = YES;
            break;
        case 2:
            firstView.hidden = YES;
            secondView.hidden = YES;
            thirdView.hidden = NO;
            break;
        default:
            break;
    }
}

实现效果如下：